1. Field of the Invention
The present invention relates to an intelligent network (IN) capable of providing services to Internet users. More particularly, the invention pertains to a service control point (SCP) having an Internet call waiting service function in the intelligent network, an Internet protocol (IP) communication apparatus which is connected with an IP network and equipped with a function for communicating with the SCP, and a service control gateway for connecting the SCP and the IP communication apparatus.
2. Description of the Related Art
A dial-up connection is available as one of the methods for making access from a public network to the Internet. With the use of the dial-up connection, a personal computer at home can be connected to the Internet over a conventional public switched telephone network (PSTN) line or an ISDN line for a desired period of time whenever necessary. Where the personal computer or another terminal apparatus is connected to the Internet using the dial-up connection, terminal user (subscriber) authentication and IP address assignment are performed by a gateway arranged for connection between the PSTN or ISDN and the Internet. While a terminal of a user (subscriber) is being connected to the Internet through the dial-up connection, a switching system accommodating the subscriber line of the user terminal can judge whether or not the subscriber line is in a busy state but the switching system cannot judge whether or not the user terminal is being connected to the Internet.
In an intelligent network (IN) which allows customization of services and provision of prompt services, its configuration is so arranged as to provide functional planes (service plane, global function plane, distributed function plane, and physical plane). These planes are specified as “Capability Set 1” (CS-1), and generation and management of services including internetworking services are specified as higher-level “Capability Set 2” (CS-2) in standardization (ITU-T Recommendations : Q.1220 to Q.1228).
The intelligent network comprises a transport layer network including a plurality of switching systems, an intelligent layer network including service control points (SCPs) which are connected with the transport layer network over a common channel signaling network, and a service management point which is connected with the SCPs. As to internetworking services standardized as “IN Capability Set 2” in ITU-T Recommendation Q.1224, methods of providing services for communication between IN networks through cooperation of service data functions and service control functions are defined primarily, but no definition is given to a method of providing communication services through cooperation of IN service control functions and the Internet.
Regarding a method of providing communication services through cooperation of the IN service control functions and the Internet, the ITU-T has proposed a scheme that, for the purpose of transmitting a service request from an Internet user to each IN service control function (SCF), a user agent function for transferring a service request from the user is provided in the Internet and a service control gateway function is provided between the Internet and the public network. However, a concrete method of providing services using these functions and a concrete method of implementing services remain to be resolved in the proposed scheme.
For diversification of communication services, it has recently been desired to provide a new kind of service through cooperation of any IN service control function and the Internet, such as an Internet call waiting (ICW) service. The ICW is a service function whereby, when a user being connected to the Internet is called, the user can receive notification of an incoming call and then indicate how the incoming call is to be further processed (e.g., rejection of incoming call, call forwarding) from a terminal of the user to the IN service control function. Then, as indicated by the user, the IN service control function continues call processing.
In the prior art of telephone networking, however, when a user line is in a busy state, a switching system cannot judge whether the busy state is due to an Internet connection call or a conventional call for telephone-to-telephone connection. In a situation where a user terminal being busy with a conventional call is called, the called terminal can normally receive a call waiting signal which is an analog signal supplied from the switching system. By way of contrast, in a situation where a user terminal being busy with an Internet connection call is called, a call waiting signal (analog signal supplied from the switching system) is treated as noise since the user terminal is sending and receiving digital signals, i.e., the called terminal cannot be notified that another call has arrived. As mentioned above, the ICW service which notifies a user being engaged in an Internet connection call of arrival of another call has not yet been implemented hitherto.